THE Inland Revenue says it will not challenge company car carbon dioxide emission figure discrepancies as the furore surrounding database sources deepens. A month after VELO joined forces with tax adviser Ernst and Young to highlight errors in vehicle CO2 figures quoted by motor manufacturers and the Society of Motor Manufacturers and Traders, Godfrey Davis (Contract Hire) has joined the fray.

Unless the differences are resolved, they could lead to disputes when the CO2-based company car tax system comes into effect in April 2002. This week the company said it was mind-boggling as to why the SMMT CO2 emission database, endorsed by the Inland Revenue as the official source of statistics, should exist when a similar database run by the Vehicle Certification Agency - part of the Department of Education, Transport and the Regions - already existed.

Godfrey Davis marketing director Nigel Underdown claimed the numerous sources of information - some official, some quasi-official and some unofficial - were causing more problems than providing answers. And while the Inland Revenue said it would accept CO2 figures from either source, figures obtained from both VELO and Godfrey Davis revealed wide discrepancies.

He claimed that while both sources were accessible through the internet - the VCA guide at www.roads.detr.gov.uk/vehicle/fuelcon/index.htm and the SMMT guide at www.smmt.co.uk - neither provided the required degree of comprehensive data and were not updated quickly enough.

The VCA says that with the launch of its internet-based site, new model CO2 updates would take place once a month, while the SMMT site presently refers only to vehicles registered from January 1998 to December last year, although it says a 'tailored service' can be provided and new model updates were expected soon.

The SMMT site adds: 'Manufacturers have supplied the CO2 information available on this site to SMMT's Automotive Data Services. Every car cannot be individually tested and there will inevitably be differences between individual cars of the same model.

'Indicative CO2 emissions figures for new car models can be viewed on the VCA website although these figures are for guidance only. The authoritative CO2 emissions figures will also be shown on the vehicle registration document (V5) for new cars registered from November.'

Underdown said: 'Godfrey Davis, along with all leasing companies, is trying to get its house in order, update systems and generally provide customers with sound and accurate information. At the moment this is not possible.

'Why the Inland Revenue has directed fleets towards a non-governmental source of reference in the first place when there should be a perfectly adequate Government site is a mystery.'

An Inland Revenue source said: 'By 2002 the new V5 document will carry a vehicle's official CO2 figure. For existing company cars we will accept examples of CO2 emission discrepancies uncovered.'